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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/integral.html" title="cpp/concepts/integral"><span class="t-lines"><span>integral</span></span></a></div></div></td></tr>
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<tr class="t-nv-h2"><td colspan="5"> Comparison concepts</td></tr>
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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/movable.html" title="cpp/concepts/movable"><span class="t-lines"><span>movable</span></span></a></div></div></td></tr>
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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/semiregular.html" title="cpp/concepts/semiregular"><span class="t-lines"><span>semiregular</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/regular.html" title="cpp/concepts/regular"><span class="t-lines"><span>regular</span></span></a></div></div></td></tr>
<tr class="t-nv-h2"><td colspan="5"> Callable concepts</td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/invocable.html" title="cpp/concepts/invocable"><span class="t-lines"><span>invocable</span><span>regular_invocable</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/predicate.html" title="cpp/concepts/predicate"><span class="t-lines"><span>predicate</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/relation.html" title="cpp/concepts/relation"><span class="t-lines"><span>relation</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/equivalence_relation.html" title="cpp/concepts/equivalence relation"><span class="t-lines"><span>equivalence_relation</span></span></a></div></div></td></tr>
<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="concepts/strict_weak_order.html" title="cpp/concepts/strict weak order"><span class="t-lines"><span>strict_weak_order</span></span></a></div></div></td></tr>
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<p>The concepts library provides definitions of fundamental library concepts that can be used to perform compile-time validation of template arguments and perform function dispatch based on properties of types. These concepts provide a foundation for equational reasoning in programs.
</p><p>Most concepts in the standard library impose both syntactic and semantic requirements. It is said that a standard concept is <i>satisfied</i> if its syntactic requirements are met, and is <i>modeled</i> if it is satisfied and its semantic requirements (if any) are also met.
</p><p>In general, only the syntactic requirements can be checked by the compiler. If the validity or meaning of a program depends whether a sequence of template arguments models a concept, and the concept is satisfied but not modeled, or if a semantic requirement is not met at the point of use, the program is ill-formed, <a href="language/ndr.html" title="cpp/language/ndr">no diagnostic required</a>.
</p>
<table class="t-dsc-begin">

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in  namespace <code>std</code> </div>
</td></tr>

<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Core_language_concepts">  Core language concepts </span></h5>
</td></tr>

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code><a href="header/concepts.html" title="cpp/header/concepts">&lt;concepts&gt;</a></code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/same_as.html" title="cpp/concepts/same as"> <span class="t-lines"><span>same_as</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is the same as another type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/derived_from.html" title="cpp/concepts/derived from"> <span class="t-lines"><span>derived_from</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is derived from another type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/convertible_to.html" title="cpp/concepts/convertible to"> <span class="t-lines"><span>convertible_to</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is implicitly convertible to another type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/common_reference_with.html" title="cpp/concepts/common reference with"> <span class="t-lines"><span>common_reference_with</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that two types share a common reference type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/common_with.html" title="cpp/concepts/common with"> <span class="t-lines"><span>common_with</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that two types share a common type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/integral.html" title="cpp/concepts/integral"> <span class="t-lines"><span>integral</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is an integral type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/signed_integral.html" title="cpp/concepts/signed integral"> <span class="t-lines"><span>signed_integral</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is an integral type that is signed <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/unsigned_integral.html" title="cpp/concepts/unsigned integral"> <span class="t-lines"><span>unsigned_integral</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is an integral type that is unsigned <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/floating_point.html" title="cpp/concepts/floating point"> <span class="t-lines"><span>floating_point</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is a floating-point type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/assignable_from.html" title="cpp/concepts/assignable from"> <span class="t-lines"><span>assignable_from</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is assignable from another type <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/swappable.html" title="cpp/concepts/swappable"> <span class="t-lines"><span>swappable</span><span>swappable_with</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type can be swapped or that two types can be swapped with each other <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/destructible.html" title="cpp/concepts/destructible"> <span class="t-lines"><span>destructible</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that an object of the type can be destroyed  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/constructible_from.html" title="cpp/concepts/constructible from"> <span class="t-lines"><span>constructible_from</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a variable of the type can be constructed from or bound to a set of argument types  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/default_initializable.html" title="cpp/concepts/default initializable"> <span class="t-lines"><span>default_initializable</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that an object of a type can be default constructed  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/move_constructible.html" title="cpp/concepts/move constructible"> <span class="t-lines"><span>move_constructible</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that an object of a type can be move constructed <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/copy_constructible.html" title="cpp/concepts/copy constructible"> <span class="t-lines"><span>copy_constructible</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that an object of a type can be copy constructed and move constructed  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Comparison_concepts">  Comparison concepts </span></h5>
</td></tr>

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code><a href="header/concepts.html" title="cpp/header/concepts">&lt;concepts&gt;</a></code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/boolean-testable.html" title="cpp/concepts/boolean-testable"> <i><span class="t-lines"><span>boolean-testable</span></span></i></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type can be used in Boolean contexts <br> <span class="t-mark">(exposition-only concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/equality_comparable.html" title="cpp/concepts/equality comparable"> <span class="t-lines"><span>equality_comparable</span><span>equality_comparable_with</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that operator <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy1">==</span></span></span> is an equivalence relation  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/totally_ordered.html" title="cpp/concepts/totally ordered"> <span class="t-lines"><span>totally_ordered</span><span>totally_ordered_with</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that the comparison operators on the type yield a total order <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code><a href="header/compare.html" title="cpp/header/compare">&lt;compare&gt;</a></code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="utility/compare/three_way_comparable.html" title="cpp/utility/compare/three way comparable"> <span class="t-lines"><span>three_way_comparable</span><span>three_way_comparable_with</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that operator <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy1">&lt;=&gt;</span></span></span> produces consistent result on given types  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Object_concepts">  Object concepts </span></h5>
</td></tr>

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code><a href="header/concepts.html" title="cpp/header/concepts">&lt;concepts&gt;</a></code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/movable.html" title="cpp/concepts/movable"> <span class="t-lines"><span>movable</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that an object of a type can be moved and swapped <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/copyable.html" title="cpp/concepts/copyable"> <span class="t-lines"><span>copyable</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that an object of a type can be copied, moved, and swapped  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/semiregular.html" title="cpp/concepts/semiregular"> <span class="t-lines"><span>semiregular</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that an object of a type can be copied, moved, swapped, and default constructed <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/regular.html" title="cpp/concepts/regular"> <span class="t-lines"><span>regular</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a type is regular, that is, it is both <a href="concepts/semiregular.html" title="cpp/concepts/semiregular"><code>semiregular</code></a> and <a href="concepts/equality_comparable.html" title="cpp/concepts/equality comparable"><code>equality_comparable</code></a> <br> <span class="t-mark">(concept)</span> </td></tr>

<tr>
<td colspan="2"> <h5> <span class="mw-headline" id="Callable_concepts">  Callable concepts </span></h5>
</td></tr>

<tr class="t-dsc-header">
<td colspan="2"> <div>Defined in header <code><a href="header/concepts.html" title="cpp/header/concepts">&lt;concepts&gt;</a></code> </div>
</td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/invocable.html" title="cpp/concepts/invocable"> <span class="t-lines"><span>invocable</span><span>regular_invocable</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>  specifies that a callable type can be invoked with a given set of argument types  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/predicate.html" title="cpp/concepts/predicate"> <span class="t-lines"><span>predicate</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a callable type is a Boolean predicate  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/relation.html" title="cpp/concepts/relation"> <span class="t-lines"><span>relation</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a callable type is a binary relation  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/equivalence_relation.html" title="cpp/concepts/equivalence relation"> <span class="t-lines"><span>equivalence_relation</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a <a href="concepts/relation.html" title="cpp/concepts/relation"><code>relation</code></a> imposes an equivalence relation  <br> <span class="t-mark">(concept)</span> </td></tr>

<tr class="t-dsc">
<td>  <div class="t-dsc-member-div"><div><a href="concepts/strict_weak_order.html" title="cpp/concepts/strict weak order"> <span class="t-lines"><span>strict_weak_order</span></span></a></div><div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div></div>
</td>
<td>   specifies that a <a href="concepts/relation.html" title="cpp/concepts/relation"><code>relation</code></a> imposes a strict weak ordering  <br> <span class="t-mark">(concept)</span> </td></tr>
</table>
<p>Additional concepts can be found in <a href="iterator.html#C.2B.2B20_iterator_concepts" title="cpp/iterator">the iterators library</a>, <a href="iterator.html#Algorithm_concepts_and_utilities" title="cpp/iterator">the algorithms library</a>, and <a href="ranges.html#Range_concepts" title="cpp/ranges">the ranges library</a>.
</p>
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